Prostaglandins play a major role in the inflammation process, and the inhibition of prostaglandin production, especially production of PGG.sub.2, PGH.sub.2 and PGE.sub.2, has been a common target of antiinflammatory drug discovery. However, common non-steroidal antiinflammatory drugs (NSAIDs) that are active in reducing the prostaglandin-induced pain and swelling associated with the inflammation process, are also active in affecting other prostaglandin-regulated processes not associated with the inflammation process. Thus, use of high doses of most common NSAIDs can produce severe side effects, including life-threatening ulcers, that limit their therapeutic potential. An alternative to NSAIDs is the use of corticosteroids, which have even more drastic side effects, especially when long-term therapy is involved.
Previous NSAIDs have been found to prevent the production of prostaglandins by inhibiting enzymes in the human arachidonic acid/prostaglandin pathway, including the enzyme cyclooxygenase (COX). Recently, the sequence of another heretofore unknown enzyme in the human arachidonic acid/prostaglandin pathway has been reported by T. Hia and K. Nielson, Proc. Natl. Acad. Sci. USA, 89, 7384 (1992) and named "cyclooxygenase II (COX II)" or "prostaglandin G/H synthase II". The discovery of an inducible enzyme associated with inflammation provides a viable target of inhibition which more effectively reduces inflammation and produces fewer and less drastic side effects. Cyclooxygenase II is inducible by cytokines or endotoxins and such induction is inhibited by glucocortoids (J. Masferrer, et al, Proc. Natl. Acad. Sci. USA, 89, 3917 (1992)). The 6-methoxy-2-napthylacetic acid metabolite of nabumetone has been found by E. Meade et al to selectively inhibit the COX II enzyme (J. Biol. Chem., 268, 6610 (1993)). In addition, Futaki et al (Gen. Pharmac., 24, 105 (1993)) has reported that N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide is antiinflammatory and lacks gastric side effects.
The substituted thiophene compounds disclosed herein selectively inhibit cyclooxygenase II over cyclooxygenase I and relieve the effects of inflammation. These compounds, in addition, do not display substantial inhibition of cyclooxygenase I and produce a reduced amount of side effects.
Selected symmetrical 3,4-bis(phenyl, napthyl or substituted phenyl) thiophenes are known.
Preparation of a wide-variety of asymmetric biaryl compounds including substituted thiophene, furan and pyrrol heterocyles is described in U.S. Pat. No. 4,990,647 having a suggested utility as precursors for brighteners, pharmaceuticals, plant protection active compounds and liquid crystal materials.
U.S. Pat. No. 4,757,084 describes to Biftu analogs of 2,5-diaryl tetrahydrothiophenes having activity as PAF-antagonists which are said to be linked to physiological processes associated with a large group of diseases including inflammatory disease.
U.S. Pat. No. 5,196,532 to Wuest et al, describes 2,4-diaryl substituted thiophenes for cosmetics and the treatment of dermatological disorders.
U.S. Pat. No. 4,427,693 to Haber, describes antiinflammatory 4,5-diarylthiophene-2-methanamines. U.S. Pat. No. 4,432,974 to Haber, describes antiinflammatory and analgesic 2,3-diaryl-5-silylthiophenes. U.S. Pat. No. 4,302,461 to Cherkofsky, describes antiinflammatory 2,3-diarylthiophenes substituted with various alkyl sulfur radicals at position 5. U.S. Pat. No. 4,381,311 to Haber, describes antiinflammatory 4,5-diarylthiophene-2-methanols.
2,3-Diaryl-5-halo thiophenes are described in U.S. Pat. No. 4,590,205 to Haber, as analgesic or antiinflammatory agents. 4-Fluorophenyl and 4-methylsulfonylphenyl are among the various substituted phenyl groups that define the diary groups. U.S. Pat. No. 4,820,827 to Haber, describes 2,3-diaryl-5-bromo thiophenes, and specifically 5-bromo-2-(4-methylthiophenyl)-3-(4-fluorophenyl)thiophene, as having antiinflammatory and prostaglandin synthetase inhibitory activity for use in the treatment of inflammation and dysmenorrhea.
Japanese publication 4,335,767 describes photosensitive 3,4-bis(diazosubstitutedphenyl)thiophene pigments for use in photocopiers or facsimile receivers.
U.S. Pat. No. 3,743,656 to Brown et al, a CIP of U.S. Pat. No. 3,644,399, describes thiophene and furan derivatives having antiinflammatory activity, including ethyl 3,4-diphenylthiophene-2-propionate.
The above documents describing antiinflammatory activity show continuing efforts to find a safe and effective antiinflammatory agent.